Face bow

ABSTRACT

A FACE BOW FOR RECORDING THE POSITIONAL RELATIONSHIP BETWEEN A DENTAL PATIENT&#39;&#39;S TEETH AND HIS JAW HINGE AXIS COMPRISING A CROSSBAR AND ADJUSTABLE SIDE ARMS FASTENABLE TO THE CROSSBAR SO AS TO EXTEND AWAY THEREFROM, ON OPPOSITE SIDES OF THE PATIENT&#39;&#39;S FACE, TO TERMINATION NEAR THE ENDS OF HIS JAW HINGE AXIS. AT THEIR REAR, THE SIDE ARMS HAVE OPEN-SIDED POCKETS INTO WHICH DENTAL COMPOUND CAN BE PACKED. THE FACE BOW INCLUDES TWO POINTERS WHICH CAN BE HEATED AND WORKED INTO PACKET COMPOUND IN THE SIDE ARM   POCKETS UNTIL THEIR POINTS ARE POSITIONED ON THE SKIN AT THE ENDS OF THE PATIENT&#39;&#39;S JAW HINGE AXIS.

J55. 19, 1971 L. BAUM 3,555,684

FACE BOW Filed March 19, 1969 AL'QKO 540M INVEN'IOR.

United States Patent A face bow for recording the positional relationship between a dental patients teeth and his jaw hinge axis comprising a crossbar and adjustable side arms fastenahle to the crossbar so as to extend away therefrom, on opposite sides of the patients face, to termination near the ends of his jaw hinge axis. At their rear, the side arms have open-sided pockets into which dental compound can be packed. The face bow includes two pointers which can be heated and worked into packet compound in the side arm pockets until their points are positioned on the skin at the ends of the patients jaw hinge axis.

BACKGROUND OF THE INVENTION This inventon relates generally to dental apparatus, and more particularly to a face bow of simplified form suitable for use in determining the position of a patients jaw hinge axis relative to his teeth or jaws and transferring the resulting information to a dental articulator to permit duplication of his jaw structure therein.

Various types of face bows have heretofore been devised for recording the positional relationship between the ends of a dental patients jaw hinge axis and his teeth. Such face bows have invariably been characterized by the presence of a crossbar adapted to carry a bite fork and two adjustable side arms, which parts cooperate to permit positioning of the side arms either side of a dental patients face with their rearwardly disposed ends adjacent the re spective ends of his jaw hinge axis. This positioning of the face bow is accomplished with the aid of a bite typically prepared by mounting softened dental wax or modeling compound on said bite fork, taking an impression from the patients teeth, hardening the wax or modeling compound, and, where necessary, trimming the hardened material. When the face bow is ready for positioning on the dental patient, the bite is inserted in his mouth and supported in bite position against the occlusing surfaces of his upper teeth. The bite can be manually supported in this position, or the patient can accomplish the same result by clamping the bite fork between his teeth.

The side arms of the above-described conventional face bow are coarsely adjustable for proper positioning either side of a dental patients face by means of length-adjusting and angular positioning steps familiar to dentists and others skilled in the dental arts, after which pointers, or styli, mounted at the rear ends of the sidearms, are, in many cases, brought into contact with previously marked locations of the patients jaw hinge axis on his skin. An orbital (nasal) pointer can be mounted on the crossbar of the face bow, and point-oriented with a mark on the patients nose, if desired. The aforesaid styli are connected to the side arms of the'face bow through an adjustable mounting assembly of greater or lesser complexity, the chief function of which is to provide means for finely adjusting the stylus points to positions of coincidence with the ends of the patients jaw hinge axis. The assembly can be made up of any of various combinations of cooperating parts which function to move the styli in different directions under the manipulating fingers of a dentist or dental technician.

While some stylus-mounting assemblies are more complex than others, all require the hand manipulations of Patented Jan. 19, 1971 ice cooperating parts, a steadiness and delicacy of touch and a certain amount of acquired expertise for most satisfactory operation. Even the least complex of the face bows, however, in the deft hands of a highly skilled dentist, is rather difficult to use because of the above-indicated necessity for hand manipulating a variety of parts. Moreover, in some cases, the manipulation of various parts of the face bow, for fine adjustment of the styli positions, can cause instrument tremors of sufficient magnitude to upset adjustments previously made, this being particularly true in the case of face bows employing springs, or other tension members, in their mounting assemblies. Finally, the more cooperating parts in the stylus mounting assembly of a face how has, the more expensive the face bow is to manufacture, particularly since such parts must obviously be made to high standards of precision.

SUMMARY OF THE INVENTION The face bow of the present invention is similar to known face bows in certain respects, but radically different therefrom in others. More specifically, my novel face bow is of greatly simplified construction by comparison with, and cheaper to manufacture than, adjustable face bows of conventional type, and can be manipulated with great accuracy, in a fraction of the time required for the adjustment of such conventional face bows, with a minimum of effort.

My novel face bow has, in its preferred form, a crossbar essentially equivalent to that described above, and a pair of side arms pivotally movable thereabout and telescopically adjustable for length. The face bow differs markedly from all known face bows, however, in the shapes of the rear ends of its side arms, and it lends itself to a unque and extremely simple technique for permitting a pair of pointers, or styli, to be rapidly adjusted to point contact with the ends of a dental patients jaw hinge axis previously recorded on his skin. In this connection, each of the side arms of the face how has a C-shaped, opensided pocket, or hollow, at its rearwardly disposed end, of sufficient Width to hold a large enough body of packed dental wax or modeling compound (hereinafter compound) to firmly anchor one of the aforesaid pointers in place after the latter has been embedded in the compound in a manner presently to be described. The C- shaped hollows at the ends of the side arms are thus used in lieu of the mounting assemblies heretofore employed for the final positioning of styli in dental face bows. This technique of using a pointer, or stylus, in conjunction with a C-shaped side arm hollow, is the ultimate in simplicity, typically involving merely the steps of packing the hollow with softened compound, warming the shaft of the stylus and working it downwardly into the compound in the hollow while manipulating the point of the stylus toward a previously marked spot on the patients face at the end of his jaw hinge axis, then permitting the compound to harden. After the compound hardens, the stylus is fixed firmly in place with its point indexing the end of the patients jaw hinge axis. After this procedure has been completed either side of the patients face (and a conventional orbital pointer has, if desired, been properly positioned and adjusted on the face how), the face bow is ready for removal from the patient and transfer to a dental articulator for replication of the proper geometric relationship between the patients teeth and his jaw hinge axis in the articulator.

As will be apparent from the foregoing, a principal object of this invention is to provide a simple and lightweight face bow, capable of use with a minimum of skill and effort, for determining the relative positions of the ends of a dental patients jaw hinge axis and his teeth or jaws for transfer to a dental articulator.

It is another object of the invention to provide such a face bow of relatively inexpensive construction, capable of yielding accurate results in a fraction of the time required for usage of a face bow of more conventional type.

Other objects, features, and advantages of the invention will become apparent in the light of subsequent disclosures herein.

BRIEF DESCRIPTION OF THE DRAWING FIG. 1 is a perspective view of a preferred embodiment of a face bow (complete with bite fork) in accordance with this invention.

FIG. 2 is a view, partly in section, of the face bow, taken along the plane indicated at 2 on FIG. 1, showing the manner in which a side arm of the latter is adjustable for length.

FIG. 3 is a fragmentary view of the face bow, showing the rearwardly disposed ends of the side arms of the latter in positions of exaggerated closeness, and C-shaped hollows at the ends of the side arms packed with modeling compound, and showing, additionally, a pair of thin styli, or pointers, for determining the ends of a patients jaw hinge axis, one of the pointers being shown in a position of approach to the packed compound in one of the C- shaped hollows, and the other pointer being shown embedded in the compound in the second of the C-shaped hollows with its point contacting one end of a patients jaw hinge axis, the positions of the jaw hinge axis being depicted on the drawing as phantom line circles.

DESCRIPTION OF THE PREFERRED EMBODIMENT Considering now the drawing in greater detail, there is shown generally at a preferred embodiment of a face bow in accordance with this invention. Face bow 10 comprises a crossbar 12, a pair of identical side arms 14, and a bite fork 16 with a handle 18. The parts of the face bow are of lightweight metal construction, the crossbar 12 being of round cross section and adapted to receive an adjustable clamp for mounting the bite fork thereon in the manner illustrated in FIG. 1. As those skilled in the art will appreciate, the bite fork is adapted to carry an impression of the patients upper teeth (not shown), by means of which it can be supported against those teeth for positioning of the face bow with its crossbar disposed transversely in front of the patients face. Adjustable clamp 20 permits fore and aft movement of the crossbar along handle 18 of the bite fork, thereby affording a degree of coarse adjustment to the face bow to the patients face. Additionally, as will be clear from FIG. 1, clamp 20 cooperates with crossbar 12 and handle 18 of the bite fork (the latter, similarly to the former, being of round cross section to make such cooperation possible) to permit transverse movement of the bite fork along the crossbar, rotational adjustability of the bite fork relative to the crossbar and rotational adjustability of the crossbar around the handle of the bite fork, to thereby impart a still greater degree of coarse adjustability to the face bow.

As previously indicated, side arms 14 of the face bow are of identical size and shape. Each consists of a relatively short tubular segment 22 and a longer segment 24 having a shank which fits slidably within the hollow of the tubular segment and provide a means of telescopically adjusting the length of the side arm. A set screw 34 is provided in a properly tapped opening through the wall of the tubular segment, to lock the telescoping parts of the side arm together at any desired length. The tubular segment of the side arm has a clamp segment 26, adapted to slidably receive crossbar 12 and permit sliding movement of the side arm along the crossbar for proper fitting of the face bow to the faces of individual patients. Each of the side arm clamp segments has an Allen screw 28 mounted in tapped openings through confronting clamp members to permit fastening of the side arms to the cross- 4 bar (see FIGS. 1 and 2) in properly spaced positions therealong. As will be apparent, each of the side arms is individually rotatable about the crossbar, as Well as being adjustable for length, to permit coarse positioning of its rearwardly disposed end near dental patients jaw hinge axes.

Telescoping segment 24 of each of side arms 14 has a piece of flattened metal, bent into the shape of a C, integrally afiixed to its rearwardly disposed end to form an open-sided pocket, or hollow 30, adapted to receive dental compound for a purpose hereinafter revealed. As the drawing illustrates, pocket 30 is oriented for the use with its open part up (although it could conceivably be oriented the other way around, with its open part down, within the scope of the invention), and the C-shaped metal piece forming it has a penetrating opening 32 which helps anchor the compound therein.

As will be apparent from the foregoing, my novel face bow is designed for use on a dental patient after the end positions of his jaw hinge axis have been determined and marked in some manner, as, for example, directly on the sides of his face or on suitable members fixedly secured thereto. Hereinafter, for purposes of clarity, the marking will be discussed in terms of reference to the former, or direct, method of marking the patients face. As will be apparent, the face bow serves to record the space relationship between the patients teeth or jaws and the ends of his jaw hinge axis for transfer to an articulator in such fashion as to permit replication of the patients jaw structure in the articulator.

To prepare it for use on a dental patient, face bow 10 is provided with a so-called bite, which is normally prepared by mounting softened modeling compound on bite fork 16 and then taking an impression of the patients upper teeth therein. The bite is then permitted to harden, and trimmed if necessary, after which it can be inserted in the patients mouth and supported against the occlusing surfaces of his upper teeth. The crossbar of the face how can then be mounted in a position of coarse adjustment on the bite fork handle. More specifically, the cross bar can be mounted on the bite fork handle, by means of adjustable clamp 20, to extend transversely of the patients face, and spaced outwardly a suitable distance therefrom, to permit coarse adjustment of the positions of side arms 14 so that their end hollows 30 overlie the locations of the patients jaw hinge axis either side of his face. This coarse adjustment of the side arm positions can be rapidly accomplished, with a minimum of skill and effort, through rotational movement of the arms around crossbar 12, and telescopic manipulation of the side arm segments in the previously-indicated manner. As will be appreciated, the order in which the steps of the coarse face bow adjusting procedure are performed can be varied from that described above, and some, or all, of the steps can be eliminated completely under certain circumstances, as when the face bow is used repeatedly on the same patient over a relatively short period of time.

After the face bow has been properly positioned for use on a dental patent, its parts will be oriented generally as shown in FIG. 1. Either at this point, or at some previous stage of the face bow positioning procedure, each of the pockets 30 at the ends of side arms 14 is packed with softened modeling compound. The manner in which hole 32 in each of the pocket-forming segments of the side arms helps to anchor the packed compound in pockets 30 will now, it is believed, be evident. Bodies of heated and softened compound thus packed into the side arm pockets are shown at 36 in FIG. 3. Finally, the shaft of each of a pair of pointers 38 (see FIG. 3) is warmed and worked downwardly into a separate one of the bodies of compound 36, while its point is guided into contact with a previously marked end of the patients jaw hinge axis on the skin on one side of his face. While no part of the patients face appears in the drawing, the locations of the marked ends of his jaw hinge axis are shown at 40,

as phantom line circles, in FIGS. 1 and 3. FIG. 3 shows one of the pointers 38 after it has been worked to a final position of rest in one of the compound bodies 36, and the second pointer poised for embedment in the other compound body. While the first-mentioned pointer (seen at the right in FIG. 3) is shown substantially perpendicular to the side of the patients face in its final position of rest, it is not necessary that this be the case, and the pointer can deviate from such perpendicularity so long as its point remains in contact with the marked end of the patients jaw hinge axis.

For best results, face bow is employed in conjunction with an orbital (nasal) pointer (not shown), mountable on crossbar 12 by means of an adjustable clamp. Such orbital pointers (and their mounting clamps) are so well known to the dental profession as to require no detailed description here. Suffice it to say that the pointer, where employed, is positioned with its forward end adjacent an arbitrarily selected point on one side of the patients nose, in a manner and for a purpose well known to those skilled in the dental arts.

After face how 10 has been fitted to a patients face in the above-described manner, it provides a three-dimensional replication of the relative positions of the patients jaw hinge axis and his teeth or jaws. The face bow can then be removed, and placed upon a hinge action articulator with the ends of its jaw hinge axis pointers in alignment with the respective ends of the condyle axis rod or member of the articulator. Models of the patients teeth or jaws can then be placed in proper juxtaposition to the bite on the face bow, and mounted on the articulator with dental plaster or similar material, after which they will be correctly oriented with respect to the patients jaw hinge axis.

The novel face bow of this invention can, if desired, be provided with a stand, including a support rod and adjustable clamp, on which it may be placed when not in use. Accessory face bow hardware of this type, being well known to those skilled in the art, is not illustrated, or described in detail, herein. Instead of using a substance requiring heat softening treatment, such as dental wax or modeling compound, as the pointer stabilizing material in the side arm hollows of my novel face bow, any suitable substitute, such as, for example, a quick setting plaster which hardens in the cold, could be so employed within the scope of my invention.

From the foregoing description, considered conjunctively with the drawing, it will be evident that-face bow 10 is, by virtue of its absence of structural complexity and simplicity of use and functioning, operable in such a way as to achieve all of the above-noted performance advantages over presently known face bows. Thus, the face bow can be fitted to a dental patients face in a minimum of time, and with minimal effort, for accurate recordation of the orientation of his jaw hinge axis relative to the positions of his teeth or jaws. Additionally, the lack of structural complexity in the face bow contributes to a lightness of weight which makes its use possible with little or no discomfort to the patient, by comparison with the amount of discomfort accompanying the use of many face bows of presently known type.

The present invention has herein been described in considerable detail in order to comply with legal requirements for a full public disclosure of at least one of its forms. Such detailed disclosure is not, however, intended to unduly limit the scope of the patent monopoly sought to be granted. Accordingly, while my novel face bow has been illustrated in what is believed to be a preferred embodiment, it is emphasized that departures may be made therefrom within the scope of my invention. Exemplary of such departures are noncritical variations of the shapes of the face bow components; the elimination of certain structural, or other, features of the face bow not critically essential to its proper use and functioning; the addition of useful, but optional, components or accessories to the face bow; etc.

It should be emphasized, in final summary, that the scope of the present invention includes all of its variant forms encompassed by the language of the following claims. In the claims, the expressions bite and bite position are intended to have the same respective meanings as in the foregoing disclosure. While the terms pointer (or pointers) and stylus (or styli) have heretofore been employed in seemingly interchangeable fashion, I wish to make it clear that my novel face bow is not limited to use with, or the incorporation of, pointed styli such as illustrated by pointers 38 of the drawing. More specifically, pointers with other than pointed or sharpened ends for jaw hinge axis indexing utility can be employed in conjunction with, or as components, of the face bow, within the scope of my invention. For example, such pointers having cupor socket-like indexing ends, rather than pointed ends, could be so employed, as those skilled in the art will readily appreciate from an understanding of the manner in which my face bow functions.

I claim:

1. In a dental face bow having a bite plate adapted to be held in predetermined relation to a patients upper teeth, a forwardly extending handle fixed to said bite plate, a crossbar adjustably secured to said handle to extend transverse thereto forwardly of a patients face, and side arms adjustably secured to said crossbar to extend rearwardly on opposite sides of a patients face with rear end postions thereof laterally adjacent the ends of a patients jaw hinge axis; the improvement comprising:

the rear end portion of each of said side arms being formed to define an open-sided pocket opposite the adjacent end of said jaw hinge axis, said pocket containing a material capable of being in a soft but hardenable form, elongated pointer means implanted in said material to extend from said pocket toward said hinge axis and being movable in said material when in its soft form to position an end thereof in alignment with said hinge axis whereupon subsequent hardening of said material fixes said pointer means relative to said bite plate.

2. A dental face bow as defined in claim 1 wherein said pocket is defined by an open-ended cylindrical member secured to said side arm with its axis generally parallel to said hinge axis.

3. A dental face bow as defined in claim 2 wherein said member is provided with an axially extending slot through the cylindrical wall thereof whereby an elongated pointer may be moved laterally therethrough into soft material in said pocket.

4. A dental face bow as defined in claim 2 including an opening through the cylindrical wall of said member adapted to lock said material in said pocket against displacement therein.

References Cited UNITED STATES PATENTS 1,786,9l5 12/1930 McLean 32-20 2,727,307 12/ 1965 Clark 32-20 2,794,253 6/ 1957 Fitzsimmons 3220 3,056,210 10/ 1962 De Pietro 3220 ROBERT PESHOCK, Primary Examiner 

